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version 2012-09-20

ROL : ROtate Left

The bits of the source register (snd) are rotated (circular shifted) to the left by either

It is similar to SHL but the Most Significant Bits that are shifted out are reintroduced in the Least Significant bits in the same order.

In the following examples, we will rotate the bits of a register by two positions. For YASEP16, the movement of the bits can be summarised by this diagram:
For YASEP32, the principle is identical but with 32 bits instead of 16.

Here is one example using assembly code :

mov 1101101101101101b r1
rol 2 r1
After the last instruction, r1=0110110110110111b. All the bits are preserved but are in different positions.